Pump and valve actuator system and method

ABSTRACT

A double diaphragm pump including a dual spool valve actuator. A set of piston/diaphragm assemblies can be coupled to a pilot spool valve, which can direct air flow to a main spool valve. The main spool valve can direct air flow to pump chambers. Components of the pump can be manufactured by injection molding and press-fit together. The pump can include lens-shaped ports and positive-return poppet valves.

FIELD OF THE INVENTION

The invention generally relates to reciprocating pumps, such as compressed air-operated, double-diaphragm pumps, having a main spool valve and a pilot spool valve.

BACKGROUND OF THE INVENTION

Air-driven diaphragm pumps generally include two opposed pumping cavities. The pumping cavities each include a pump chamber, an air chamber, and a diaphragm extending fully across the pumping cavity defined by these two housings. Each pump chamber includes an inlet check valve and an outlet check valve. A common shaft typically extends into each air chamber to attach to the diaphragms.

An actuator valve receives a supply of pressurized air and operates through a feedback control system to alternately pressurize and vent the air chamber side of each pumping cavity through a spool valve piston. Feedback to the pilot spool valve has been provided by the position of the shaft attached to the diaphragms, which includes one or more passages to alternately vent the ends of the valve cylinder within which the control valve piston reciprocates. By selectively venting one end or the other of the cylinder, the energy stored in the form of compressed air at the unvented end of the cylinder acts to drive the piston to the alternate end of its stroke. The pressure builds up at both ends of the control valve piston between strokes. Pressurized air is allowed to pass longitudinally along the piston within the cylinder to the ends of the piston. Consequently, a clearance has typically been provided between the control valve piston and the cylinder.

The precision required of components of the double-diaphragm pumps has made it necessary to manufacture the pumps and related assemblies out of metal and precision machine the components to specific tolerances. This has resulted in high manufacturing costs and limited the markets available to this style of pump.

SUMMARY OF THE INVENTION

Embodiments of the invention provide an actuator assembly with a housing which can include a first chamber and a second chamber. A pilot spool valve can be positioned in the first chamber and a main spool valve can be positioned in the second chamber. Between the first and second chambers can be a first lens-shaped port and a second lens-shaped port. The pilot spool valve can direct air flow through the first port or the second port. Air flow through the first port can move the main spool valve toward a top portion of the second chamber and air flow through the second port can move the main spool valve toward a bottom portion of the second chamber.

In another embodiment, the invention provides a method of manufacturing a spool valve. The method can include providing for small and large ring seals, and spool valve subsections. The small ring seals can be mounted on the spool valve subsections such that the small ring seals do not pass over a portion of the spool valve that has a relatively large diameter. The large ring seals can also be mounted on the spool valve subsections. The spool valve subsections can then be press fit together to form the spool valve.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a double diaphragm pump according to one embodiment of the invention.

FIGS. 2A, 2B, 2C, and 2D are perspective views of the pump of FIG. 1.

FIGS. 3A, 3B, and 3C are perspective views of a front cover and actuator assembly of the pump of FIG. 1.

FIG. 4 is an exploded perspective view of a coupling between piston/diaphragm assemblies of the pump of FIG. 1.

FIG. 5 is an exploded perspective view of an actuator and the front cover of the pump of FIG. 1.

FIG. 6 is an exploded perspective view of a poppet valve assembly and a main housing of the pump of FIG. 1.

FIG. 7 is a cross-sectional side view of the pump of FIG. 1.

FIG. 8 is a detailed cross-sectional side view of dual o-ring seals of the pump of FIG. 1.

FIG. 9 is a detailed cross-sectional side view of the piston/diaphragm assembly of the pump of FIG. 1.

FIG. 10 is a detailed cross-sectional side view of the piston/diaphragm assembly of the pump of FIG. 1.

FIG. 11 is an exploded perspective view of an actuator of the pump of FIG. 1.

FIG. 12A is a perspective view of a pilot spool valve housing of the pump of FIG. 1.

FIG. 12B is a perspective view of a main spool valve housing of the pump of FIG. 1.

FIGS. 13A and 13B are perspective views of an assembly of the pilot spool valve housing of FIG. 12A and the main spool valve housing of FIG. 12B.

FIG. 14A is a cross-sectional side view of the main spool valve of FIG. 12B.

FIG. 14B is a cross-sectional side view of the pilot spool valve of FIG. 12A.

FIG. 15 is a cross-sectional side view of the assembly of the pilot and main spool valve housings illustrating a first extreme orientation of the pilot and main spool valves relative to the ports in the housings.

FIG. 16 is a cross-sectional side view of the assembly of the pilot and main spool valve housings illustrating a second extreme orientation of the pilot and main spool valves relative to the ports in the housings.

FIG. 17 is a cross-sectional side view of the main spool valve of FIG. 12B.

FIG. 18 is a cross-sectional side view of the pilot spool valve of FIG. 12A.

FIG. 19A is a cross-sectional side view of the pump of FIG. 1 illustrating an inlet poppet valve assembly.

FIG. 19B is a cross-sectional side view of the pump of FIG. 1 illustrating the inlet poppet valve assembly with one poppet valve open.

FIG. 20 is a cross-sectional side view of the pump of FIG. 1 illustrating an outlet poppet valve assembly.

FIG. 21 is an exploded perspective view of a quick-disconnect twist lock gas inlet fitting of the pump of FIG. 1.

FIG. 22 is a cross-sectional side view of the quick-disconnect twist lock gas inlet fitting of FIG. 21.

DETAILED DESCRIPTION OF THE INVENTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “couple” are not restricted to physical or mechanical connections or couplings.

FIGS. 1-22 illustrate a double diaphragm pump 100 according to one embodiment of the invention. The double diaphragm pump 100 can be driven by compressed air delivered by an actuator assembly 105. A main body 110 can include a first cavity 115 and a second cavity 120. A first diaphragm/piston assembly 125 can be positioned within the first cavity 115. A second diaphragm/piston assembly 130 can be positioned within the second cavity 120. The side of the first diaphragm/piston assembly 125 adjacent the first cavity 115 and the side of the second diaphragm/piston assembly 130 adjacent the second cavity 120 can be flat. The side of the first diaphragm/piston assembly 125 opposite the first cavity 115 and the side of the second diaphragm/piston assembly 130 opposite the second cavity 120 can be ribbed to provide strength to the diaphragm/piston assemblies 125 and 130.

A first shaft 135 can couple the first piston/diaphragm assembly 125 to the second piston/diaphragm assembly 130 through an opening 140 in the main body 110. A seal (not shown) can be positioned between the shaft 135 and the opening 140 in the main body 110, so that liquid in the first cavity 115 cannot enter the second cavity 120 and liquid in the second cavity 120 cannot enter the first cavity 115.

A front cover 145 can include a third cavity 150. The front cover 145 can be coupled to the main body 110, sealing the first piston/diaphragm assembly 125 between the front cover 145 and the main body 110. Once sealed, the first cavity 115 and the third cavity 150 can form a first pump chamber. A rear cover 155 can include a fourth cavity 160. The rear cover 155 can be coupled to the main body 110, sealing the second piston/diaphragm assembly 130 between the rear cover 155 and the main body 110. Once sealed, the second cavity 120 and the fourth cavity 160 can form a second pump chamber. Other configurations for the first and second pump chambers are possible, such as the chambers being formed with one or more suitable housings or covers.

In one embodiment, one or more of the main body 110, front cover 145, rear cover 155, and pistons can be injection molded of a 30-40% glass-filled polypropylene/nylon alloy. In some embodiments, as shown in FIG. 7, a premolded plastic insert 168 can provide strength to the main body 110 and can eliminate the need for ribs or relatively thick walls.

The actuator assembly 105 can be externally coupled to the front cover 145. A second shaft 165 can be coupled to the first piston/diaphragm assembly 125. The second shaft 165 can also be coupled to the actuator assembly 105. A gas inlet fitting 170 can be coupled to the actuator assembly 105.

A poppet valve housing 175 can be coupled to the main body 110 to supply liquid to and receive liquid from the first and second pump chambers. Liquid paths between the poppet valve housing 175 and the first and second pump chambers can be oversized and have no turns to promote flow of the liquid being pumped.

The poppet valve housing 175 can include a set of poppet valves 180, 182, 184, and 186, which can be positive-return poppet valves. Each poppet valve 180, 182, 184, and 186 can be held in position in a poppet valve seat 190 by a spring 188. The poppet valves 184 and 186 can be inlet valves receiving liquid from an inlet fitting 192 and providing that liquid to the first and second pump chambers. The poppet valves 180 and 182 can be outlet valves receiving liquid from the first and second pump chambers and directing that liquid to an outlet fitting 194.

In some embodiments, a dual o-ring sealing system can be used in one or more positions in the pump 100. A dual o-ring sealing system can provide a better seal, better concentricity, and failsafe operation. As shown in FIG. 8, two o-rings 198 can be used to seal the housing 110 to the back cover 155. The dual o-ring system can also be utilized to seal the housing 110 to the front cover 145. FIG. 5 illustrates the use of the dual o-ring system for sealing the actuator 105 to the front cover 145.

As shown in FIG. 1, decorative cover plate 196 can be coupled to the front cover 145 and can conceal the actuator assembly 105.

FIGS. 9 and 10 illustrate an embodiment of the piston/diaphragm assemblies 125 and 130. The piston/diaphragm assemblies 125 and 130 can each include a first piston end 400, a second piston end 405, and a diaphragm 410. The diaphragm 410 can be manufactured as a single-layer diaphragm out of materials such as Santoprene™ (a thermoplastic elastomer manufactured by Advanced Elastomer Systems), Geolast™ (a thermoplastic vulcanizate manufactured by Advanced Elastomer Systems) or buna or the diaphragm 410 can be manufactured as a dual-layer diaphragm out of materials such as Viton™ (a fluorocarbon elastomer manufactured by E.I. dupont de Nemours Company) or ethylene propylene diene monomer (“EPDM”) (as shown in FIGS. 9 and 10). A first diaphragm layer 415 and a second diaphragm layer 420 can be adhesively joined together to form each diaphragm 410.

In some embodiments, each diaphragm 410 can include six extended portions 425. The first piston end 400 can include two recesses 430 that can receive two of the extended portions 425 of diaphragm 410. The second piston end 405 can include two recesses 435 that can receive two of the extended portions 425 of diaphragm 410. The main housing 110 can include two recesses 440 that can receive two of the extended portions 425. One of the recesses 440 can receive one of the extended portions 425 for the piston/diaphragm assembly 125, while another of the recesses 440 can receive one of the extended portions 425 for the piston/diaphragm assembly 130. The front cover 145 can include a recess 445 that can receive one of the extended portions 425 of diaphragm 410, and the rear cover 155 can include a recess 450 that can receive one of the extended portions 425 of diaphragm 410.

The extended portions 425 of the diaphragm 410 can work with the recesses 430, 435, 440, 445, and 450 to hold the diaphragm 410 in place and provide an air-tight seal. As shown in FIG. 10, added hold can be provided by ridges 455 on the first piston end 400 and on the second piston end 405 which can bind the diaphragm 410 to the piston ends 400 and 405.

As shown in FIGS. 3A, 3B, and 3C, compressed air can enter the actuator assembly 105 via the twist-lock gas inlet fitting 170. The actuator assembly 105 can channel the compressed air to the third cavity 150 This compressed air can force the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 toward the rear cover 155 of the pump 100. Referring to FIG. 1, this action forces liquid that was in the first cavity 115 out of the first cavity 115 through the outlet poppet valve 180 and into the outlet fitting 194. This action also causes liquid to be drawn into the second cavity 160 through the inlet fitting 192 and around the inlet poppet valve 186.

Again referring to FIG. 1, once the first and second piston/diaphragm assemblies 125 and 130 reach the rear of their respective pump chambers, the actuator assembly 105 can channel the compressed air to the fourth cavity 160 forcing the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 toward the front cover 145 of the pump 100. This action forces liquid that was in the second cavity 120 out of the second cavity 120 past the outlet poppet valve 182 and into the outlet fitting 194. This action also causes liquid to be drawn into the first cavity 115 through the inlet fitting 192 and around the inlet poppet valve 184. Once the first and second piston/diaphragm assemblies 125 and 130 reach the front of their respective chambers, the actuator assembly 105 can channel the compressed air to the third cavity 150. This reciprocating process can continue in order to cause a substantially continuous flow of liquid out of the outlet fitting 194 of the pump 100.

FIGS. 11-13 illustrate one embodiment of the actuator assembly 105. The actuator assembly 105 can include a main housing 205. As shown in FIG. 12A, the main housing 205 can include a main chamber 210. The main housing 205 can be coupled to a pilot housing 215 which can include a pilot chamber 218, as shown in FIG. 12B. When the main housing 205 and the pilot housing 215 are attached to one another as shown in FIGS. 11, 13A, and 13B, they can form an upper air transfer chamber 220, a middle air transfer chamber 222, and a lower air transfer chamber 224, as shown in FIGS. 12A and 12B. In some embodiments, attachment of the main housing 205 and the pilot housing 215 to one another can be through hot plate welding. As shown in FIG. 11, a main spool valve 230 can be positioned in the main chamber 210 and a pilot valve 270 can be positioned in the pilot chamber 218.

In one embodiment, the main housing 205 and the pilot housing 215 can be manufactured by injection molding using a no-glass polymer with Teflon® (a tetrafluoroethylene manufactured by EI DuPont de Nemours) in order to provide high-wear, high-lubricity valve chambers.

As shown in FIG. 14A, the main spool valve 230 can include a first end 232, a second end 234, and a center portion 236. The first end 232 and the second end 234 can have a first diameter greater than a second diameter of the center 236. In one embodiment, the main spool valve 230 can include five molded-in channels 240 for receiving o-ring/ring seal assemblies. A first end o-ring 242 and a first end ring seal 244 can be mounted circumferentially around the first end 232. A second end o-ring 246 and a second end ring seal 248 can be mounted circumferentially around the second end 234. In one embodiment, a first center o-ring 250, a first center ring seal 252, a second center o-ring 254, a second center ring seal 256, a third center o-ring 258, and a third center ring seal 260 can be mounted circumferentially around the center portion 236. In some embodiments, the first, second, and third center 0-rings 250, 254, and 258, and the first, second, and third center ring seals 252, 256, and 260 can be equally spaced from one another along the center portion 236.

As shown in FIG. 14B, the pilot spool valve 270 can include five molded-in channels. A first o-ring 276, a first ring seal 278, a second o-ring 280, a second ring seal 282, a third o-ring 284, a third ring seal 286, a fourth o-ring 288, a fourth ring seal 290, a fifth o-ring 292, and a fifth ring seal 294 can be mounted circumferentially around the pilot spool valve 270. In one embodiment, the first o-ring 276 and the second o-ring 280 can be positioned closer to one another than to the third o-ring 284. Similarly, the fourth o-ring 288 and the fifth o-ring 292 can be positioned closer to one another than to the third o-ring 284.

In one embodiment, the ring seals in the main spool valve 230 and/or in the pilot spool valve 270 can be elastomeric and can be manufactured by injection molding using thermoplastic elastomer (TPE)/Teflon® self-lubricating materials. The ring seals can be flexible for assembly of the spool valves.

The rings seals in the main spool valve 230 and the pilot spool valve 270 can be in contact with the walls of their respective chambers, creating air-tight seals between each of the molded in channels 240. Spaces between the ring seals and the molded-in channels 240 on the main spool valve 230 and the pilot spool valve 270 can be used to route air flow in the spool valve chambers.

In one embodiment, as shown in FIGS. 12A and 13A, the chamber 210 can include the following “lens-shaped” or “elliptical-shaped” ports for routing air: an upper air port 300, a middle port 302, a lower port 304, an upper exhaust 306, a lower exhaust 308, a first cavity port (not shown), and a second cavity port (not shown). The “lens-shape” can be substantially the shape formed by overlaying two circles having the same diameter. This shape can be referred to as a “vesica piscis.” The “elliptical-shape” can be similar to the “vesica piscis” shape except that the ends can be more rounded. The term “lens-shape” as used herein and in the claims is intended to encompass both a vesica piscis shape and an elliptical shape.

The first cavity port can provide a sealed air link between the actuator assembly 105 and the third cavity 150 of the pump 100. The second cavity port can provide a sealed air link between the actuator assembly 105 and the fourth cavity 160 of the pump 100.

In one embodiment, as shown in FIGS. 11, 12B, 13B, 15, and 16 the chamber 218 of the pilot housing 215 can include one or more of the following “lens-shaped” ports for routing air: an upper port 320, a middle port 322, a lower port 324, an upper exhaust port 326, and a lower exhaust port 328.

The pilot spool valve 270 (as shown in FIG. 14B) can be coupled to the second shaft 165 (as shown in FIG. 1) in order to couple the pilot spool valve 270 to the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130. The position of the pilot spool valve 270 in the chamber 218 can be determined by the position of the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130. The pilot spool valve 270, in turn, can determine, by routing compressed air, the position of the main spool valve 230 in the chamber 210.

As shown in FIG. 15, when the pilot spool valve 270 is in the full upward position in the chamber 218, compressed air can enter the middle air transfer chamber 222 via an air supply port 350. Pressurized air can travel through the middle port 322 into the chamber 218 between the third ring seal 286 and the fourth ring seal 290. The pressurized air can then pass through the lower port 324 into the lower air transfer chamber 224. The pressurized air can continue through the lower air transfer chamber 224 and into the lower port 304. The pressurized air can enter the chamber 210 below the main spool valve 230 and the second end spool 234. The pressurized air can force the main spool valve 230 to rise in chamber 210. Air in the chamber 210 above the main spool valve 230 can be forced through the upper port 300 and into the upper air transfer chamber 220. This air can then pass through the upper port 320 and into the chamber 218 between the second ring seal 282 and the third ring seal 286. When the pilot spool valve 270 is in this upper position, the upper exhaust port 326 can be located between the second ring seal 282 and the third ring seal 286. This can allow the air from above the main spool valve 230 to exit the actuator assembly 105 through the upper exhaust port 326.

Once the main spool valve 230 reaches the upper position in the chamber 210, pressurized air from the air supply port 350 can pass through the middle port 302 into the chamber 210. The pressurized air can enter the chamber 210 between the second center ring seal 252 and the third center ring seal 256. When the main spool valve 230 is in this position the first cavity port can also be located between the second center ring seal 252 and the third center ring seal 256 and can allow pressurized air to flow into the third cavity 150 of the pump 100. This pressurized air can force the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 toward the rear cover 155 of the pump 100.

Air in the fourth cavity 160 can be forced through the second cavity port and into the main spool valve chamber 210 between the first center ring seal 252 and the second center ring seal 256. As shown in FIG. 16, the main spool valve chamber 210 can include an upper angled wall 360 extending between a narrower center section 362 and a wider end section 364. When the main spool valve 230 is in the upper position, the first center ring seal 252 can be adjacent to the angled wall 360, breaking the air-tight seal between the second center ring seal 256 and the first end ring seal 244. This allows air to flow around the first center ring seal 252 and out of the actuator assembly 105 through the upper exhaust port 306 (as shown in FIG. 13A).

As the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 move toward the rear cover 155 of the pump 100, they pull the pilot spool valve 270 toward the bottom of the chamber 218. Once the third ring seal 286 of the pilot spool valve 270 passes over the middle port 322 (as shown in FIG. 15), the flow of air in the pump 100 can reverse.

As shown in FIG. 16, when the pilot spool valve 270 is in the full downward position in the chamber 218, compressed air can enter the middle air transfer chamber 222 via the air supply port 350. Pressurized air can travel through the middle port 322 into the chamber 218 between the second ring seal 282 and the third ring seal 286. The pressurized air then can pass through the upper port 320 into the upper air transfer chamber 220. The pressurized air can continue through the upper air transfer chamber 220 and into the upper port 300. The pressurized air can enter the chamber 210 above the main spool valve 230 and the first spool end 232. The pressurized air can force main spool valve 230 to move lower in chamber 210. Air in the chamber 210 below the main spool valve 230 can be forced through the lower port 304 and into the lower air transfer chamber 224. This air can then pass through the lower port 324 and into the chamber 218 between the third ring seal 286 and the fourth ring seal 290. When the pilot spool valve 270 is in this lower position, the lower exhaust port 328 can be located between the third ring seal 286 and the fourth ring seal 290. This can allow the air from below the main spool valve 230 to exit the actuator assembly 105 through the lower exhaust post 328.

Once the main spool valve 230 reaches the lower position in the main spool valve chamber 210, pressurized air from the air supply port 350 can pass through the middle port 302 into the chamber 210. The pressurized air can enter the chamber 210 between the first center ring seal 252 and the second center ring seal 256. When the main spool valve 230 is in this position, the second cavity port can also be located between the first center ring seal 252 and the second center ring seal 256 and can allow pressurized air to flow into the fourth cavity 160 of the pump 100. This pressurized air can force the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 toward the front cover 145 of the pump 100.

Air in the third cavity 150 can be forced through the first cavity port and into the chamber 210 between the second center ring seal 256 and the third center ring seal 260. The chamber 210 includes a lower angled wall 370 between the narrower center section 362 and a wider lower end section 372. When the main spool valve 230 is in the lower position, the third center ring seal 260 can be adjacent the lower angled wall 370 breaking the air-tight seal between the second center ring seal 256 and the second end ring seal 248. This can allow air to flow around the third center ring seal 260 and out of the actuator assembly 105 via the lower exhaust port 308, as shown in FIG. 13A.

As the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 move toward the front cover 145 of the pump 100, they can push the pilot spool valve 270 toward the top of the chamber 218. Once the third ring seal 286 of the pilot spool valve 270 passes over the middle port 322, the flow of air in the pump can reverse.

Performance of the actuator assembly 105 can be enhanced by the use of “lens-shaped” ports. The lens-shaped ports can provide a larger open area, allowing a higher volume of air through the port. In some embodiments, the height of one or more of the ports can be narrower than the height of one or more of the ring seals. In some embodiments, this can result in faster opening and closing of the ports and substantially complete isolation between adjacent air channels. This can also result in the ring seals not catching on the edges of the port, in some embodiments, resulting in less wear and longer life.

Some embodiments of the invention can offer a number of advantages related to the assembly and manufacture of the actuator assembly 105. For example, in one embodiment, components of the actuator assembly 105 can be manufactured by injection molding and the main spool valve 230 and the pilot spool valve 270 can be hand assembled by press-fitting. The housing of actuator assembly 105 can include two injection molded components, the housing 205 and the housing 215. The lens-shaped ports can be molded into the housing 205 and the housing 215 and require no machining, resulting in lower manufacturing costs.

FIG. 17 illustrates one embodiment of the main spool valve 230 including the following injection-molded subcomponents: two ends 710, a first center piece 715, and a second center piece 720. The first center piece 715 and the second center piece 720 can be press-fit together with the second center o-ring 254 and the second center ring seal 256 between them. The second center o-ring 254 and second center ring seal 256 can be assembled with minimal stretching, because they are not passed over a lip 725 on the main spool valve 230. Additionally, the second center o-ring 254 and the second center ring seal 256 are not passed over the ends 710, which would require a relatively large amount of stretching, which could compromise the performance and life of the second center o-ring 254 and the second center ring seal 256. The ends 710 can receive the first center o-ring 250, the first center ring seal 252, the third center o-ring 258, and the third center ring seal 260 with minimal stretching. The two ends 710 can then be press-fit assembled to the first center piece 715 and the second center piece 720. The first end o-ring 242 and the first end ring seal 244 can be rolled onto one of the main spool valve ends 710. The second end o-ring 246 and the second end ring seal 248 can be rolled onto the other main spool valve end 710 in order to complete the assembly of the main spool valve 230.

FIG. 18 illustrates one embodiment of the pilot spool valve 270 including the following injection-molded subcomponents: two ends 810, a first center piece 815, and a second center piece 820. The first center piece 815 and the second center piece 820 can be press-fit together with the third o-ring 284 and the third ring seal 286 between them. The third o-ring 284 and the third ring seal 286 can be assembled with minimal stretching, because they do not pass over a lip 825 on the pilot spool valve 270. The ends 810 can receive the first center o-ring 280, the first center ring seal 282, the third center o-ring 288, and the third center ring seal 290 with minimal stretching. The ends 810 can then be press-fit assembled to the first center piece 815 and the second center piece 820. The first o-ring 276 and the first ring seal 278 can be rolled onto one of the ends 810. The fifth o-ring 292 and the fifth ring seal 294 can be rolled onto the other end 810 in order to complete the assembly of the pilot spool valve 270.

FIG. 19A illustrates one embodiment of a poppet valve assembly 900 for a liquid inlet. The poppet valves 184 and 186 (as also shown in FIG. 1) of the poppet valve assembly 900 can be positive return poppet valves. The poppet valves 184 and 186 can be seated against poppet valve seats 190. The poppet valves 184 and 186 can be held against the poppet valve seats 190 by springs 188. In one embodiment, each poppet valve 184 and 186 can include four alignment fins 910. A liquid inlet 915 can supply a non-pressurized liquid to the poppet valve assembly 900. A vacuum can be created above the poppet valve 184 by the first pistol/diaphragm assembly 125 moving toward the front cover 145 of pump 100. This vacuum can cause the poppet valve 184 to pull off the poppet valve seat 190 and compress the spring 188. The poppet valve 184 can maintain alignment with the poppet valve seat 190 via the four alignment fins 910, which can remain in contact with the poppet valve seat 190 and can ensure that the poppet valve 184 returns to the poppet valve seat 190 in the proper position to create a tight seal. The alignment fins 910 can have a sufficient length such that were the spring 188 to compress fully, the alignment fins 190 would remain in contact with the poppet valve seat 190. This can result in more stable and colinear alignment and can prevent the poppet valve 184 from becoming lodged in an open position. Once the poppet valve 184 has separated from the poppet valve seat 190, liquid can be drawn, by the vacuum, around the poppet valve 184 and into the first cavity 115 (as shown by the arrows in FIG. 19B).

Once the piston/diaphragm 125 reaches the front cover 145 of pump 100 and begins moving toward the rear cover 155 of pump 100, the vacuum can be removed and the poppet valve 184 can be returned to the poppet valve seat 190 by the spring 188. Once seated, the poppet valve 184 can prevent liquid from exiting the first cavity 115 through the liquid inlet 915.

FIG. 20 illustrates one embodiment of a poppet valve assembly 1000 for a liquid outlet. The poppet valves 180 and 182 (as also shown in FIG. 1) can be positive return poppet valves. The poppet valve 180 can be seated against a poppet valve seat 190. The poppet valve 180 can be held against the poppet valve seat 190 by a spring 188. Liquid in the pump 100 can become pressurized by the first piston/diaphragm assembly 125 pushing toward the front of the first cavity 115. The poppet valve 180 can be pushed off its poppet valve seat 190 compressing the spring 188. The poppet valve 180 can maintain alignment with the poppet valve seat 190, via the four alignment fins 910, which can remain in contact with the poppet valve seat 190, ensuring that the poppet valve 180 returns to the poppet valve seat 190 in the proper position to create a tight seal. The alignment fins 910 can have a sufficient length such that were the spring 188 to compress fully, the alignment fins 190 would remain in contact with the poppet valve seat 190. This can result in more stable and colinear alignment and can prevent the poppet valve 184 from becoming lodged in an open position. Once the poppet valve 180 is separated from its poppet valve seat 190, the pressurized liquid in the first cavity 115 can flow around the poppet valve 180 and into a liquid outlet 1015. When the piston/diaphragm assembly 125 reaches the end of its travel range (e.g., the rear of the first cavity 115), the liquid can lose pressure. The spring 188 can then force the poppet valve 180 back to its poppet valve seat 190. Once seated, the poppet valve 180 can prevent liquid in a liquid outlet 1015 from flowing back into the pump 100.

Working together, the inlet poppet valve assembly 900 and the outlet poppet valve assembly 1000 can allow the pump 100 to draw liquid into the pump 100 from the liquid inlet 915 and to pump liquid out of the liquid outlet 1015.

One embodiment of the dual diaphragm pump 100 can include the inlet poppet valve assembly 900 and the outlet poppet valve assembly 1000 and can allow both the first cavity 115 and the second cavity 120 to share a common liquid inlet 915 and a common liquid outlet 1015. The first piston/diaphragm assembly 125 can draw liquid into the first cavity 115 at the same time as the second piston/diaphragm assembly 130 can expel liquid from the second cavity 120. During this time, the poppet valve 184 can be unseated to allow liquid to flow into the first cavity 115. The poppet valve 186 can be seated to prevent liquid in the second cavity 120 from escaping into the liquid inlet 915.

As shown in FIG. 20, the poppet valve 180 can be seated to prevent liquid in a liquid outlet chamber 1020 from entering the first cavity 115. The poppet valve 182 can be unseated to allow the pressurized liquid in the second cavity 120 to escape to the liquid outlet chamber 1020 and the liquid outlet 1015.

Once the first piston/diaphragm assembly 125 and the second piston/diaphragm assembly 130 reach the end of their travel range, they can reverse direction. The first piston/diaphragm assembly 125 can expel liquid from the first cavity 115 at the same time as the second piston/diaphragm assembly 130 can draw liquid into the second cavity 120. During this time, the poppet valve 186 can be unseated to allow liquid to flow into the second cavity 120. The poppet valve 184 can be seated to prevent liquid in the first cavity 115 from escaping into the liquid inlet 915.

The poppet valve 182 can be seated to prevent liquid in the liquid outlet chamber 1020 from entering the second cavity 120. The poppet valve 180 can be unseated to allow the pressurized liquid in the first cavity 115 to escape to the liquid outlet chamber 1020 and the liquid outlet 1015.

One embodiment of the quick disconnect twist-lock gas inlet fitting 170 is illustrated in FIGS. 21 and 22. A housing 500 including a twist-lock guide 505 can receive a barbed hose fitting 510. The barbed hose fitting 510 can be conical in shape to provide an air-tight seal when coupled with a gas hose (not shown). A large o-ring 512 fits over the barbed hose fitting 510 and forms an air-tight seal between the barbed hose fitting 510 and the housing 500. An air poppet valve 515 can be biased by a spring 520 within the barbed hose fitting 510. A small o-ring 525 can mount on the air poppet valve 515, creating a seal when biased by the spring 520. A fitting retention collar 530 can mount to the housing 500 to guide a gas hose over the barbed hose fitting 510 and into the twist lock guide 505.

Parts of the pump 100 that are not constructed of plastics and are positioned in the path of the liquid can be constructed of Hastelloy™ (manufactured by Haynes International, Inc.) to improve temperature, stress, and corrosion resistance. In some embodiments, valves and seals of pump 100 can be constructed of Santoprene™ (manufactured by Advanced Elastomer Systems), Geolast™ (manufactured by Advanced Elastomer Systems), buna, Viton™ (manufactured by E.I. dupont de Nemours Company) or EPDM.

Some embodiments of the pump 100 can be used in car washes and can have overall dimensions of 7.37 inches in depth by 4.1 inches in width by 4.58 inches in height. In one embodiment, the pump 100 can have an air inlet operating pressure range of 20 pounds per square inch (“psi”) to 100 psi while other embodiments of the pump 100 can have air inlet operating pressures as high as 150 psi. In one embodiment, the pump 100 can withstand backpressure of up to 1200 psi. In one embodiment, priming of the pump 100 can occur at 15 psi when the pump 100 is dry and 20 psi when the pump 100 is wet. In some embodiments the pump 100 can withstand liquid temperatures in excess of 110° F. and ambient temperatures in excess of 130° F.

In some embodiments, the pump 100 can discharge seven gallons per minute (“GPM”) at 60 psi with an air charge of 100 psi. In other embodiments, the pump 100 can discharge 10 GPM with an air charge in excess of 100 psi. In one embodiment, the pump 100 can operate substantially continuously at 120 psi air charge and, over its useful life, can discharge 100,000 gallons at 70 psi and an air charge of 100 psi.

Various features and advantages of the invention are set forth in the following claims. 

1. An actuator assembly comprising: a housing including a first chamber and a second chamber; a pilot spool valve positioned in the first chamber; a main spool valve positioned in the second chamber; and a first port and a second port between the first chamber and the second chamber, at least one of the first port and the second port having a lens shape; the pilot spool valve directing air flow through one of the first port and the second port, air flow through the first port moving the main spool valve toward a top portion of the second chamber, air flow through the second port moving the main spool valve toward a bottom portion of the second chamber.
 2. The actuator assembly of claim 1 wherein the second chamber includes a third port and a fourth port; and wherein the main spool valve directs air flow through one of the third port and the fourth port.
 3. The actuator assembly of claim 1 wherein at least one of the housing, the pilot spool valve, and the main spool valve is injection molded.
 4. The actuator assembly of claim 1 wherein a first plurality of ring seals are positioned around the pilot spool valve in the first chamber and a second plurality of ring seals are positioned around the main spool valve in the second chamber.
 5. The actuator assembly of claim 4 wherein the first plurality of ring seals and the second plurality of ring seals are injection molded.
 6. The actuator assembly of claim 1 wherein a plurality of ring seals constructed of thermoplastic elastomer and a self-lubricating material are positioned around the pilot spool valve and the main spool valve.
 7. The actuator assembly of claim 1 wherein the housing is constructed by injection molding using a no-glass polymer with tetrafluoroethylene.
 8. The actuator assembly of claim 1 wherein no metal is used in constructing the actuator.
 9. A method of manufacturing a spool valve, the method comprising: providing small ring seals, large ring seals, and spool valve subsections; mounting the small ring seals on the spool valve subsections such that the small ring seals do not pass over a portion of the spool valve having a relatively large diameter; mounting the large ring seals on the spool valve subsections; and press fitting the spool valve subsections together to form the spool valve.
 10. The method of claim 9 and further comprising injection molding at least one of the small ring seals, the large rings seals, and the spool valve subsections.
 11. The actuator assembly of claim 9 and further comprising constructing at least one of the small ring seals and large ring seals of thermoplastic elastomer and tetrafluoroethylene.
 12. A double diaphragm pump comprising: a first pump chamber including a first diaphragm; a second pump chamber including a second diaphragm; a first shaft coupled between the first diaphragm and the second diaphragm; and an actuator assembly including: a housing having a first chamber and a second chamber; a pilot spool valve positioned in the first chamber; a second shaft coupled between the pilot spool valve and the first diaphragm; a main spool valve positioned in the second chamber; and a first port and a second port between the first chamber and the second chamber; the pilot spool valve directing air flow through one of the first port and the second port, air flow through the first port moving the main spool valve toward a top portion of the second chamber, air flow through the second port moving the main spool valve toward a bottom portion of the second chamber.
 13. The pump of claim 12 wherein at least one of the first port and the second port has a lens shape.
 14. The pump of claim 12 wherein the actuator assembly includes a third port and a fourth port in the second chamber; and the main spool valve directs air flow through one of the third port and the fourth port.
 15. The pump of claim 12 wherein at least one of the housing, the pilot spool valve, and the main spool valve is injection molded.
 16. The pump of claim 12 wherein at least one of the first diaphragm and second diaphragm is constructed of at least one of thermoplastic elastomer, thermoplastic vulcanizate, buna fluorocarbon elastomer, and ethylene propylene diene monomer.
 17. The pump of claim 12 wherein at least one of the first pump chamber and the second pump chamber is constructed by injection molding an approximately 30 to 40 percent glass-filled polypropylene/nylon alloy.
 18. The pump of claim 12 wherein a plurality of ring seals seal the pilot spool valve in the first chamber and the main spool valve in the second chamber.
 19. The pump of claim 18 wherein the plurality of ring seals are injection molded.
 20. The pump of claim 12 wherein the pilot spool valve is coupled to the shaft by press fitting.
 21. The pump of claim 12 wherein the actuator assembly is constructed without using any metal.
 22. The actuator assembly of claim 12 wherein a plurality of ring seals constructed of thermoplastic elastomer and tetrafluoroethylene are positioned around the pilot spool valve and the main spool valve.
 23. The actuator assembly of claim 12 wherein the housing is constructed by injection molding using a no-glass polymer with tetrafluoroethylene.
 24. The actuator assembly of claim 12 wherein no metal is used in constructing the actuator.
 25. A diaphragm pump comprising: at least one pump chamber; at least one diaphragm separating each one of the at least one pump chambers into an air chamber and a pumping chamber; a shaft coupled to the at least one diaphragm; and an actuator assembly including: a housing having a first chamber and a second chamber; a pilot spool valve positioned in the first chamber; a second shaft coupled between the pilot spool valve and the first diaphragm; a main spool valve positioned in the second chamber; and a first port and a second port between the first chamber and the second chamber; the pilot spool valve directing air flow through one of the first port and the second port, air flow through the first port moving the main spool valve toward a top portion of the second chamber, air flow through the second port moving the main spool valve toward a bottom portion of the second chamber.
 26. The pump of claim 25 wherein at least one of the first port and the second port has a lens shape.
 27. The pump of claim 25 wherein the actuator assembly includes a third port and a fourth port in the second valve chamber; and wherein the main spool valve directs air flow through one of the third port and the fourth port.
 28. The pump of claim 25 wherein at least one of the housing, the pilot spool valve, and the main spool valve is injection molded.
 29. The pump of claim 25 wherein a plurality of ring seals seal the pilot spool valve in the first chamber and the main spool valve in the second chamber.
 30. The pump of claim 29 wherein the plurality of ring seals are injection molded.
 31. The pump of claim 25 wherein the pilot spool valve is coupled to the shaft by press fitting.
 32. The pump of claim 25 wherein the actuator assembly is constructed without using any metal.
 33. The actuator assembly of claim 25 wherein a plurality of ring seals constructed of thermoplastic elastomer and a self-lubricating material are positioned around the pilot spool valve and the main spool valve.
 34. The actuator assembly of claim 25 wherein the housing is constructed by injection molding using a no-glass polymer with a self-lubricating material.
 35. The actuator assembly of claim 25 wherein no metal is used in constructing the actuator.
 36. A positive return poppet valve assembly comprising: a valve housing; a spring; a plurality of valves including a plurality of alignment fins for each of the plurality of valves, the plurality of alignment fins having a first length greater than a second length of the spring; and a plurality of valve seats including guides that engage the plurality of alignment fins.
 37. The positive return poppet valve assembly of claim 32 wherein the plurality of valves are constructed of at least one of thermoplastic elastomer, thermoplastic vulcanizate, buna fluorocarbon elastomer, and ethylene propylene diene monomer.
 38. The positive return poppet valve assembly of claim 32 wherein the plurality of valves includes a first inlet valve for a first pump chamber.
 39. The positive return poppet valve assembly of claim 34 wherein the plurality of valves includes a second inlet valve for a second pump chamber.
 40. The positive return poppet valve assembly of claim 35 wherein the plurality of valves includes a first outlet valve for a first pump chamber.
 41. The positive return poppet valve assembly of claim 36 wherein the plurality of valves includes a second outlet valve for a second pump chamber.
 42. The positive return poppet valve assembly of claim 36 wherein the first inlet valve and the second inlet valve share a liquid inlet fitting.
 43. The positive return poppet valve assembly of claim 37 wherein the first outlet valve and the second outlet valve share a liquid outlet fitting.
 44. The positive return poppet valve assembly of claim 32 wherein the differential between the first length and the second length prevents the plurality of valves from becoming lodged in an open position.
 45. A method of operating an actuator assembly comprising a housing including a first chamber and a second chamber, a pilot spool valve positioned in the first chamber, a main spool valve positioned in the second chamber, and a first port and a second port between the first chamber and the second chamber, the method comprising: directing air flow through one of the first port and the second port, at least one of the first port and the second port having a lens shape; moving the main spool valve, via air flow through the first port, toward a top portion of the second chamber; and moving the main spool valve, via air flow through the second port, toward a bottom portion of the second chamber.
 46. The method of claim 41 and further comprising directing air flow through one of a third port and a fourth port in the second chamber.
 47. The method of claim 41 and further comprising sealing sections of the first chamber by a plurality of ring seals.
 48. The method of claim 41 and further comprising sealing sections of the second chamber by a plurality of ring seals.
 49. A method of actuating a dual-diaphragm pump, the method comprising: coupling a pilot valve to a first diaphragm, the pilot valve in a first chamber and the first diaphragm in a first pump chamber; coupling the first diaphragm to a second diaphragm, the second diaphragm in a second pump chamber; compressing a volume of air into an air supply port; channeling the volume of air to move a main valve from a lower position in a second chamber to an upper position in the second chamber; forcing the first diaphragm from a front position in the first pump chamber to a rear position in the first pump chamber, the second diaphragm from a front position in the second pump chamber to a rear position in the second pump chamber, and the first diaphragm pulling the pilot valve from an upper position in the first chamber to a lower position in the first chamber; channeling the first volume of air to move the main valve from an upper position in the second chamber to a lower position in the second chamber; and forcing the first diaphragm from a rear position in the first pump chamber to a front position in the first pump chamber, the second diaphragm from a rear position in the second pump chamber to a front position in the second pump chamber, and the first diaphragm pushing the pilot valve from a lower position in the first chamber to an upper position in the first chamber.
 50. The method of claim 49 and further comprising directing the volume of air into a lower section of the second chamber.
 51. The method of claim 49 and further comprising directing the volume of air into an upper section of the second chamber.
 52. The method of claim 49 and further comprising channeling a second volume of air from the air supply port into the second chamber.
 53. The method of claim 49 and further comprising directing the volume of air into the first pump chamber.
 54. The method of claim 49 and further comprising directing the volume of air into the second pump chamber.
 55. A pump housing, the housing comprising: a main body including a premolded plastic insert; a front cover; and a rear cover; at least one of the main body, the front cover, and the rear cover constructed by injection molding an approximately 30 to 40 percent glass-filled polypropylene/nylon alloy.
 56. The pump housing of claim 55 wherein dual o-rings seal the main body to the front cover.
 57. The pump housing of claim 55 wherein dual o-rings seal the main body to the rear cover.
 58. The pump housing of claim 55 wherein dual o-rings seal an actuator assembly to the front cover. 